Resins have excellent characteristics such as resistance to impact, light permeability, and lightweight properties. Thus, resins are potentially useful for devices themselves and components constituting devices. However, resins are generally liable to be thermally-deformed.
Optical materials for radically curable compositions suitable for cast molding are disclosed in JP 2012-251032A (Dec. 20, 2012), the contents of the entirety of which are incorporated herein by this reference.